Motherboard with voltage regulator for supporting DDR2 memory modules and DDR3 memory modules

ABSTRACT

An exemplary motherboard includes a driving module, at least two first slots arranged for mounting two first type of memories, at least two second slots arranged for mounting two second type of memories, and a voltage regulator. The driving module is electronically connected to the at least two first slots, the at least two second slots, and the voltage regulator in turn via a channel. The first type of memories and the second type of memories are alternatively mounted on the motherboard, the voltage regulator detects which type memory is currently mounted on the motherboard and outputs voltages suitable for the type of memory mounted on the motherboard accordingly.

CROSS-REFERENCES TO RELATED APPLICATION

Relevant subject matter is disclosed in a co-pending U.S. patentapplication with application Ser. No. 11/766,105, filed on Jun. 21,2007, and entitled “MOTHERBOARD”, which is assigned to the same assigneeas this patent application.

BACKGROUND

1. Field of the Invention

The present invention relates to motherboards, and particularly to amotherboard for supporting different types of memories.

2. Description of Related Art

Currently, a typical personal computer comprises a motherboard,interface cards, and peripheral accessories. The motherboard is theheart of the personal computer. On the motherboard, in addition to thecentral processing unit (CPU), the chip set, and the slots forinstalling the interface cards, it further includes memory module slotsfor installing memory modules.

Due to constant change in the computer industry, memories used in thecomputer have changed from DDR2 (Double Data Ram II) used in the past tohigher speed memories such as DDR3 (Double Data Ram III).

Because DDR2 is cheaper than DDR3, the main board with DDR2 still is indemand in the market. The difference in operating DDR2 and DDR3includes: DDR2 utilizes 1.8V VDD and 0.9V VTT, while DDR3 utilizes 1.5VVDD and 0.75V VTT. Currently, no motherboard is compatible with bothDDR3 and DDR2. As a result, more motherboards have to be fabricatedadding to production cost.

What is needed is to provide a motherboard capable of flexiblysupporting different types of memories.

SUMMARY

An exemplary motherboard includes a driving module, at least two firstslots arranged for mounting two first type of memories, at least twosecond slots arranged for mounting two second type of memories, and avoltage regulator. The driving module is electronically connected to theat least two first slots, the at least two second slots, and the voltageregulator in turn via a channel. The first type of memories and thesecond type of memories are alternatively mounted on the motherboard,the voltage regulator detects which type memory is currently mounted onthe motherboard and outputs voltages suitable for the type of memorymounted on the motherboard accordingly.

Other advantages and novel features of the present invention will becomemore apparent from the following detailed description of preferredembodiment when taken in conjunction with the accompanying drawings, inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a motherboard for supporting differenttypes of memories in accordance with a first embodiment of the presentinvention having four slots and a voltage regulator;

FIG. 2 is a schematic view of a motherboard for supporting differenttypes of memories in accordance with a second embodiment of the presentinvention having four slots and a voltage regulator; and

FIG. 3 is a circuit diagram of the voltage regulator of FIG. 1 and FIG.2.

DETAILED DESCRIPTION

Referring to FIG. 1, a motherboard for supporting different types ofmemories in accordance with a first embodiment of the present inventionincludes a driving module 50 such as a north bridge chipset, two DDR2slots 10, 20, two DDR3 slots 30, 40 and a voltage regulator 200,arranged in that order. The DDR2 slots 10, 20 are used for installingtwo first type of memories, such as two DDR2 memories. The DDR3 slots30, 40 are used for installing two second type of memories, such as twoDDR3 memories. The north bridge chipset 50 is connected to the two DDR2slots 10, 20, the two DDR3 slots 30, 40, and the voltage regulator 200in turn via a channel A.

Referring to FIG. 2, a motherboard for supporting different types ofmemories in accordance with a second embodiment of the present inventionincludes a north bridge chipset 100, two DDR3 slots 60, 70, and two DDR2slots 80, 90 and a voltage regulator 200, arranged in that order. TheDDR3 slots 60, 70 are used for installing two second type of memories,such as two DDR3 memories. The DDR2 slots 80, 90 are used for installingtwo first type of memories, such as two DDR2 memories. The north bridgechipset 100 is connected to the two DDR3 slots 60, 70, the two DDR2slots 80, 90, and the voltage regulator 200 in turn via a channel B.

The first type of memories and the second type of memories arealternatively mounted on the motherboard. The voltage regulator 200provides working voltage for the DDR2 slots or the DDR3 slots accordingto different types of memories mounted on the motherboard. In thepractice, the DDR2 slots and the DDR3 slots may be arranged in aplurality ways. The signal rise time is indicated for each possiblearrangement along with an indication of having non-monotoniccharacteristic or not in the table below:

Slots array manner

Signal rise 0.667 1.159 0.616 1.150 0.716 0.597 time(ns) Non-monotonicNo Yes Yes No Yes NoAccording to the table, the direction of the arrowhead represents thealignment order of the DDR2 and DDR3 slots. The signal rise times usingthe motherboards in accordance with the first and second embodiments ofthe present invention are respectively 0.667 ns and 0.597 ns, and do nothave a non-monotonic characteristic during signal transmission, so thetwo embodiments are the two optimal choice.

Referring to FIG. 3, the voltage regulator 200 comprises a controller 12having a feedback terminal and an output terminal, a filter 14 having aninput terminal and an output terminal, a linear voltage regulator 16,and a feedback circuit 18. The output of the controller 12 is connectedto the input terminal of the filter 14, and the filter 14 outputs a VDDvoltage at the output terminal thereof. The VDD voltage is transmittedto the linear voltage regulator 16, and is converted into a VTT voltagetransmitted to the DDR2 slots and the DDR3 slots. The output terminal ofthe filter 14 is connected to the DDR2 slots and the DDR3 slots toprovide the VDD voltage.

The feedback circuit 18 comprises two transistors Q1 and Q2, fourresistors R1˜R4, and a feedback resistor R5. The transistors Q1 and Q2are PMOS transistors. The gate of the transistor Q1 is connected toground terminals of the DDR2 slots and to a 5V power source via theresister R1. The source of the transistor Q1 is grounded. The drain ofthe transistor Q1 is connected to the 5V power source via the resistorQ2 and to the gate of the transistor Q2. The gate of the transistor Q2is connected to ground terminals of the DDR3 slots. The source of thetransistor Q2 is grounded. The drain of the transistor Q2 is groundedvia the resistors R3 and R4 in turn and also connected to the feedbackterminal of the controller 12 via the resistor R3. The feed backresistor R5 is connected between the output terminal of the filter 14and the feedback terminal of the controller 12. The resistances of theresistors R1˜R4 are approximately 4.7 Kohms, 4.7 Kohms, 2.4 Kohms, and1.2 Kohms respectively, and the resistance of the feedback resistor R5is approximately 1.1 Kohms. The operation of the feedback circuit 18 ispremised upon the fact that the level of the feedback voltage Vfb isstable, in this preferred embodiment, the level of the feedback voltageVfb is 0.78V.

When the DDR2 memories are mounted in the DDR2 slots, the DDR3 slots areidle. The ground terminals of the DDR2 slots generate a ground signal.The transistor Q1 is turned on, and the transistor Q2 is turned off.According to the following formula: VDD=Vfb*(R5+R4)/R4, the voltageoutput from the controller 12 is 1.8V. The voltage is provided to thefilter 14, which filters and rectifies the voltage to provide a smoothvoltage output. The VDD is provided to the feedback circuit 18 and theDDR2 memories mounted in the DDR2 slots. The linear voltage regulator 16is configured to receive the VDD voltage and provide a regulated outputvoltage of VTT (0.9V), which is provided to the DDR2 memories.

When the DDR3 memories are mounted in the DDR3 slots, the DDR2 slots areidle. The ground terminals of the DDR3 slots generate the ground signal.The transistor Q1 is turned off, the transistor Q2 is turned on, and theresistor R3 is connected in the circuit. According to the followingformula: VDD=Vfb*(R5+Rx)/Rx, wherein Rx=(R3+R4)/R3*R4, the voltageoutput from the controller 12 is 1.5V. The voltage is provided to thefilter 14, which filters and rectifies the voltage to provide a smoothvoltage output. The VDD is provided to the feedback circuit 18 and theDDR3 memories mounted in the DDR3 slots. The linear voltage regulator 16is configured to receive the VDD voltage and provide a regulated outputvoltage of VTT (0.75V), which is provided to the DDR3 memories.

Thus, the motherboard is capable of utilizing either the DDR2 or theDDR3, thus enhancing production capability and reducing production cost.

The foregoing description of the exemplary embodiments of the inventionhas been presented only for the purposes of illustration and descriptionand is not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Many modifications and variations are possiblein light of the above teaching. The embodiments were chosen anddescribed in order to explain the principles of the invention and theirpractical application so as to enable others skilled in the art toutilize the invention and various embodiments and with variousmodifications as are suited to the particular use contemplated.Alternative embodiments will become apparent to those skilled in the artto which the present invention pertains without departing from itsspirit and scope. Accordingly, the scope of the present invention isdefined by the appended claims rather than the foregoing description andthe exemplary embodiments described therein.

1. A motherboard for supporting different types of memories, comprising:a driving module; at least two first slots arranged for mounting twofirst type of memories and connected to the driving module via achannel, wherein the two first type of memories are adjacent to eachother, each first slot comprises a ground terminal generating a groundsignal when the first type of memory is mounted therein; at least twosecond slots arranged for mounting two second type of memories andconnected to the driving module via the channel, wherein the two secondtype of memories are adjacent to each other, each second slot comprisesa ground terminal generating the ground signal when the second type ofmemory is mounted therein, and the first type of memories and the secondtype of memories are alternatively mounted on the motherboard; and avoltage regulator connected to the driving module via the channel todetect which type of memory is mounted on the motherboard, and outputvoltages suitable for the detected type of memory mounted on themotherboard, the voltage regulator comprising: a feedback circuitreceiving the ground signal from the ground terminal of the first slotor the second slot and outputting a constant feedback voltage accordingto the ground signal; a controller comprising a feedback terminal toreceive the constant feedback voltage and convert the constant feedbackvoltage to a first voltage, and an output terminal to output the firstvoltage to the first slot or the second slot; and a linear voltageregulator comprising an input terminal to receive the first voltage fromthe output terminal of the controller and convert the first voltage to asecond voltage, and an output terminal to output the second voltage tothe first slot or the second slot.
 2. The motherboard as claimed inclaim 1, wherein the two first slots are DDR2 slots, and the two secondslots are DDR3 slots.
 3. The motherboard as claimed in claim 2, whereinthe at least two first slots and the at least two second slots areconnected to the channel in turn, and the at least two first slots arecloser to the driving module than the at least two second slots.
 4. Themotherboard as claimed in claim 2, wherein the at least two second slotsand the at least two first slots are connected to the channel in turn,and the at least two second slots are closer to the driving module thanthe at least two first slots.
 5. The motherboard as claimed in claim 2,wherein the voltage regulator comprises: a filter comprising an inputterminal connected to the output terminal of the controller to receivethe first voltage from the controller, and an output terminal connectedto the DDR2 slots and the DDR3 slots to provide the first voltage to theDDR2 slots and the DDR3 slots via filtering, a feedback resistor isconnected between the output terminal of the filter and the feedbackterminal of the controller; and the feedback circuit comprising a firsttransistor and a second transistor, the gate of the first transistorconnected to ground terminals of the DDR2 slots and to a power sourcevia a first resistor, the source of the first transistor grounded, thedrain of the first transistor connected to the power source via a secondresistor and to the gate of the second transistor, the gate of thesecond transistor also connected to ground terminals of the DDR3 slots,the source of the second slot grounded, the drain of the secondtransistor grounded via a third resistor and a fourth resistor in turnand also connected to the feedback terminal of the controller via thethird resistor.
 6. The motherboard as claimed in claim 5, wherein thefirst transistor and the second transistor are PMOS transistors.
 7. Themotherboard as claimed in claim 5, wherein the resistances of the firstto the fourth resistors are approximately 4.7 Kohms, 4.7 Kohms, 2.4Kohms, and 1.2 Kohms respectively, and the resistance of the feedbackresistor is approximately 1.1 Kohms.
 8. The motherboard as claimed inclaim 5, wherein a feedback voltage at the feedback terminal of thecontroller is 0.78V.